Zinc tellurite glasses



Jan. 21, 1969 M. J. REDMAN ZINC TELLURITE GLASSES Filed Feb. 20, 1967 7O Te0 Somple Thickness 1.7 mm

0.5 IO L5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Wave lengih (microns) COMmmCEmCOLE FIG. I

5 a q .l R. O m m M m m w 9 m 1 I fi 0. n Cl d 7 mm 2 m ...w l h h O T 0. m km 0- p %m %m l 50 50 65 6S z I l I} MICHAEL J. REDMAN cowmwwEwcu FIG. 2

Wave length (microns) BY M,%M7 v n ATTORNEYS United States Patent 3,423,326 ZINC TELLURITE GLASSES 3,423,326 Patented Jan. 21, 1969 TABLE II.-DISSIPATION FACTORS AND RESISTIVITIES MEASURED AT 1 Kc.

Michael J. Redmau, Belmont, Mass, assignor t Kennef cott Copper Corporation, New York, N.Y., a corporation of New York 5 30 0. 00203 a. 45x10 Filed Feb. 20, 1967, Ser. No. 617,362 3? 8333i? Z fiifi US. Cl. 252-301.6 3 Claims g Int. Cl. C09k 1/04; C03c 3/28 94 010043 1 94 1o 26 0. 00237 3 50 1o 65 017 011 ABSTRACT OF THE DISCLOSURE 6 ("7 d3 9s 0: 0029 3117x10 5 1 N 25 0. 00194 A glass having high dielectric constant, density and 0 111 s e refractive index and particularly suitable as a laser host T O giving secondary em1ss1ons at 1.06 1. when doped with Nd, repare mm Spec pure 6 2 is composed f Z O a d T o FIG. 1 of the drawings shows a transmission range for a typical glass containing 70% TeO between 0.38 and 6.6 1. with two absorption bands at 3.35 and 4.5 1. This invention consists in a novel glass composition FIGURE 2 of the drawings absorption 1 5- consisting essentially of tellurium oxide and Zinc oxide, ml of (3112+ and doped Z1110 telllll'lte A characterized by a high dielectric constant, density and 20 sPectl'um for commercfally avall' refractive index. Glasses of this formulation are useful for laser glasses Wlth 81110011 and boron OXldeS as th optical and instrumentation purposes and are also exmam constltllntstremely well suited as laser host materials. When doped The solublllty of e1rth 8 z a 1n the with a rare earth metal, strong fluorescence is observed, z glasses of 1115 lnVeIlllOn ranges to more than at 1,06,, wh th dditive i Nd O 10% by weight of the final doped glass when starting with When either tellurium oxide or zinc oxide is melted a 010 f 1 percent ZnO in a ZnO-TeQ mixture and and cooled below its melting point, neither solidifies to a substituting Nd O for ZnO on an equal weight bas s. This vitreous glass, but each rather crystallizes. We have found coupled with the broad transmissivlty range provides an that mixtures containing minor molar fractional amounts unusually favorable envlfofiment for stlmlllawd emlS- of ZnO, when melted and cooled, form a. clear arnorsion. The glasses of this invention when doped with arare phous glass composition. Specifically best results are obearth oxide such as Nd O appear to provide an excellent tained with mixtures containing between about 20 a d laser material, as shown by Table III in which the fluores- 40 percent ZnO (molar). Mixtures containing smaller and cent characteristics of glasses of this invention are comlarger amounts of ZnO also exhibit glass-like properties 5 pared with a doped standard glass (American Optical but it should be noted that at 50% ZnO a crystalline com- 3 #3538).

TABLE III Weight Output 7 (time for Glass percent Cone. atoms Output normalized drop inI Nd N d/cc. Io'Yo to cone. of from In to X10" Nd, X10"1 Io' A0 #3538 5.0 47.2 42-48 0. 9-1.0 500-000 ZnO:TeO-2 (:65 molar) 1.1 20.9 75-82 3.6-3.9 150 pound ZnTeO is formed. The precise limits of ZnO content can readily be determined by routine experimentation within the guidelines set forth herein.

The glasses of the instant invention are specifically characterized by a density of about 5.35 gr./cc., a refractive index of about 2.0 (5892 A., 23 C.), a dielectric constant as shown in Table I. Dielectric loss and A.C. resistivities are set forth in Table 11.

TABLE I.DIELECTRIC CONSTANTS OF ZINC TELLURIIE GLASSES Dielectric Constant Sample, mol 'Iempera- (Frequency, c.p.s.) percent TeOz ture C.)

30 19. 51 19. 49 19. 40 96 20. 18 20. 00 19. 90 25 21. 22 21. 20 21. 18 95 21. 77 21. 75 21. 72 30 21. 18 21. O4 20. 96 94 21. 80 21. 76 21. 72 26 21. 41 21.32 21.21 96 22. 10 21. 98 21. 82 65 (0.1% Cu) 30 18. 95 18.90 18.82 96 19. 41 19. 33 19. 22 65 (1% Ndzoa) 25 18. 45 18.39 18. 34 111 19. 58 19. 20 19. 02

*Prepared from spec-pure T901.

In measuring the fluorescent activity of the glasses reported in Table III, a sample of glass is exposed to a beam of light from a xenon flash tube. The intensity I of fluorescent radiation normal to the beam is then measured and plotted against time -r. The initial intensity at 7:0 is I The output is taken as 1 1- where the value of 1 is the time for I to drop to l e The glasses of this invention may be manufactured by melting together a mixture of zinc oxide and tellurium oxide. The glass reported in Table III, consisting of 35 mol percent ZnO and 65 mol percent T e0 is made by mixing the ZnO and TeO in the weight ratio of 21.5 ZnO to 78.5 T802, melting them together in a platinum or other inert crucible over a gas flame and then cooling slowly, and annealing at 250-300 C. (which is below the transition temperature of 400 C.

Doped glasses are prepared by adding Nd O in an amount up to about 10% by weight, to the mixture prior to melting.

Preferably the tellurium oxide is purified prior to compounding, by dissolving it in an aqueous solution of sodium hydroxide, and filtering the solution. Hydrochloric acid is then added to reprecipitate the TeO which is then filtered, rinsed with distilled water, and dried at 200 C.

From the foregoing data it will be seen that the glasses of this invention, upon excitation from a xenon flash lamp, emit far more effectively than the standard, notwithstanding a lesser dopant concentration.

Although this invention has been described with specific reference to the presently preferred embodiment, it is contemplated that modifications will readily occur to those skilled in the art and familiar With the principles herein set forth. For instance, it is contemplated that dopants other than Nd may be used, such as other rare earths or transition metals, or mixtures of them. Also, it 10 to secure by Letters Patent:

1. Zinc tellurite glasses consisting essentially of a major molar proportion of Te0 and between about 20 and about 40 molar percent of ZnO.

2. Fluorescent glass as defined by claim 1 containing a rare earth metal oxide in an amount sufiicient for fluorescent activity.

3. Fluorescent glass as defined by claim 2 containing Nd O in an amount sufiicient for fluorescent activity.

References Cited UNITED STATES PATENTS 2,763,559 9/1956 Weissenberg et al. 10647 2,978,417 4/1961 Larach 25230l.6

FOREIGN PATENTS 81,391 5/1956 Netherlands.

OTHER REFERENCES 15 Stanworth: Tellurite Glasses, J. Soc. Glass Tech., vol.

36 (1952), pp. 217-241, TP 845 S 678.

HELEN M. MCCARTHY, Primary Examiner.

0 U.S. Cl. X.R. 

